[media] s5p-fimc: Ensure proper s_power() call order in the ISP datapaths

Since the FIMC-IS firmware communicates with an image sensor directly
through the ISP I2C bus controllers the sub-devices power supplies
cannot be simply enabled from left to right or disabled from right
to left along the processing pipeline. Thus a subdev index to call
s_power() on is looked up from a table, rather than doing the op call
based on increasing/decreasing indexes.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>